As far as I know it's basically treated as a physical attack in every way, shape, and form until the final number which is then turned into elemental damage (and possibly checked for resist as well). Duoing the elemental plateau with a warrior, he -seemed- to take less damage than I do when I solo them, though that may be attributed to the fact that we learned that Demoralizing Shout reduces the elemental damage they output.

This could be due to elementals performing physical attacks as well.
I think some hits (done by a fire/air elemental) can be blocked by shield.

But I'm not sure ... never paid close attention to that.

There's a particular kind of attack that's physical-but-elemental; the attack is mitigated by armor, but gets reported as elemental damage. The first case I noticed of this was the arcane elementals in Dire Maul. The first boss in Mana Tombs does physical-shadow, and the explody mana-elementals in Karazhan between Curator and Aran do physical-arcane.

Curiously, attacks of this class are mitigated by armor but apparently cannot be blocked by a shield.

Placebo? Add's do natur damage.

And as far as resistance goes, Heroic resist is not needed realy, horror stories tend to blow thing's up. Just good geared people. As far as serp shrine goes, and further and mag, I cant realy say has im no there yet. And nature on maulgar is not needed, as you could solo the fucker at lvl 60 -_-

I'm nearly positive it is arcane.

I debated making a new thread, but I'm not sure exactly how to get hit defense cap with frost resistance gear. Here is what I have so far (or am in the process of getting)

Head: Iceguard Helm + KoT enchant (16 defense rating 17 dodge rating)
Neck : Touch of Frost
Shoulders : Icebane pauldrons + Scryer Exalted enchant (15 defense rating 10 dodge rating)
Chest : Icebane Breastplate - could get Iceguard but its lower defense rating, but 18 more frost resistance, 150 health enchant
Back : Glacial Cloak, or I could wear my Devilshark Cape, probably will do that as Frost resistance is fairly high
Wrist : Icebane Bracers + 12 defense rating enchant
Hands : Icebane Gauntlets + Vindicator's Armor Kit (8 defense rating)
Waist : Crimson Girdle of the Indomitable, no frost options to my knowledge
Legs : Icebane Leggings, again more defense compared to Iceguard, probably put a Clefthide kit on that.
Boots : Boots of Elusion or Battlescar, doesn't matter it seems.
Ring1 : Hailstone Band
Ring2 : Ramaladni's Icy Grasp - could get the Frozen Eye, -3 sta +10 frost resistance
Trinket1 : Styleen's Impeding Scarab
Trinket2 : Adamantine Figurine
Weapon : King's Defender
Shield : The Plague Bearer
Ranged : Assassin's Shuriken of the Champion

I feel like I am missing something here, I'd mix up some gear options with Ctprofiles but that doesn't seem to be working at all here. Oh and obviously I would have a Flask of Fortification on, so thats another 30 defense rating.

From the sounds of it I suppose I just have too much frost resistance anyway and I could wear more normal gear for the different in defense and just rely on the aura to take me over the rest of the way. We haven't had many Hydross attempts due to attendance issues so far, so I wasn't sure exactly what to shoot for.

It most definitely is.